Scala/sgf-parsing declares scala-parser-combinators but tests can't find it

bruce-wayne · December 15, 2024, 3:57am

SGF Parsing in Scala on Exercism declares a dependency on "org.scala-lang.modules" %% "scala-parser-combinators" % "2.1.0", but when I submit a solution using the library, fails to find it.

We received the following error when we ran your code:
-- [E008] Not Found Error: /mnt/exercism-iteration/src/main/scala/Sgf.scala:2:18 ---------
2 |import scala.util.parsing.combinator.RegexParsers
  |       ^^^^^^^^^^^^^^^^^^
  |value parsing is not a member of util - did you mean util.Sorting? or perhaps util.Using or util.hashing?

I don’t think there’s a permalink to a failed iteration, so, please let me know if you need more information.

DanKH · June 23, 2025, 10:18am

Having the exact same issue now about a year later :-)

IsaacG · June 23, 2025, 4:35pm

@rabestro Would you have any ideas here?

rabestro · June 23, 2025, 4:44pm

I have a few unsolved exercises on the Scala track, and this one is among them :)

I suggest the case of error is Scala 2 => Scala 3 migration.

The AI confirms this:

The Core of the Problem: A Deprecated Library

The root cause of this issue is that the scala.util.parsing.combinator library, which includes RegexParsers, is no longer part of the standard Scala library as of Scala 2.13 and later versions.

Let’s create an issue on GitHub:

github.com/exercism/scala

SGF Parsing exercise is broken due to missing scala-parser-combinators dependency after Scala 3 migration

opened 04:53PM - 23 Jun 25 UTC

rabestro

**Problem Description:** The `sgf-parsing` exercise currently fails to compile …due to a `Not Found Error` for `scala.util.parsing.combinator.RegexParsers`. This issue appears to be a direct result of the track's migration from Scala 2.12 (or earlier) to Scala 3. A typical error message encountered is: ``` [E008] Not Found Error: /path/to/Sgf.scala:2:18 2 |import scala.util.parsing.combinator.RegexParsers | ^^^^^^^^^^^^^^^^^^ | Not found: type parsing ``` **Root Cause:** Starting with Scala 2.13, the `scala-parser-combinators` library was modularized and extracted from the standard library. Consequently, it is no longer available by default in Scala 3. Any code relying on `RegexParsers` or other classes from this package now requires an explicit dependency to be added to the project's build configuration. The current test runner and build environment for this exercise have not been updated to include this dependency, making the provided stub and example solutions that use `RegexParsers` uncompilable. **Suggested Actions for Resolution:** To make this exercise solvable again for students, the maintainers will need to update the exercise's configuration. There are two potential paths forward: **Option 1: Add the Missing Dependency (Recommended for fastest fix)** The most direct solution is to add the `scala-parser-combinators` library to the exercise's build configuration. 1. **Modify `build.sbt`:** Add the following line to the `build.sbt` file for the `sgf-parsing` exercise: ```sbt libraryDependencies += "org.scala-lang.modules" %% "scala-parser-combinators" % "2.3.0" ``` *(Note: Version `2.3.0` is the latest version compatible with Scala 3. Please verify the appropriate version at the time of fix.)* **Option 2: Modernize the Exercise (Long-term improvement)** While adding the dependency is a quick fix, it relies on a library that is no longer considered the standard for parsing in modern Scala. A more forward-looking solution would be to update the exercise to use a contemporary parsing approach. 1. **Update Stub and Example Solution:** Rewrite the exercise stub and reference solution to not depend on `scala-parser-combinators`. This could involve: * Using a modern, high-performance parsing library like **FastParse** or **Cats Parse**. This would require adding one of those dependencies instead. * Rewriting the solution to use standard string manipulation and `scala.util.matching.Regex`. This would remove external dependencies entirely and test a different set of skills. 2. **Update Documentation:** The exercise's `.docs/instructions.md` and hint files may need to be updated to guide the student towards the new expected approach. Given the goal of getting the track back to a fully working state, **Option 1** is likely the most pragmatic first step.